The present application claims priority under 35 U.S.C. xc2xa7119 to Korean Application No. 2000-18900 and Korean Application No. 2001-6986 filed respectively on Apr. 11, 2000 and Feb. 13, 2001, which are hereby incorporated by reference in their entirety for all purposes.
1. Field of the Invention
The present invention relates to a semiconductor wafer cleaning apparatus and method of cleaning semiconductor wafers using the same, and more particularly, to a semiconductor wafer cleaning apparatus employing a marangoni dryer and a method of cleaning semiconductor wafers using the same.
2. Description of the Related Art
A process for cleaning a semiconductor wafer is necessary to remove residual chemicals, small particles, and contaminants produced during the manufacture of integrated circuits. In particular, a cleaning process for removing fine contaminants attached to the surface of a semiconductor wafer is very important when highly-integrated circuits are fabricated.
Semiconductor wafer cleaning techniques include a chemical solution treatment process, a de-ionized water cleaning process, and a drying process. The chemical solution treatment process is a process for treating a semiconductor wafer with a chemical solution, and the washing process is a process for washing the semiconductor wafer treated with the chemical solution, with de-ionized water, and the drying process is a process for drying the washed semiconductor wafer. Among these processes, since defects caused by shortcomings in the drying process have a larger size and repeatedly occur in a pattern, integrated circuits may malfunction or function poorly.
As integrated circuits become more complicated, a conventional spin dryer using centrifugal force in the drying process reaches limits in its performance, so an IPA vapor dryer using isopropyl alcohol (IPA) has been suggested. However, when an IPA vapor dryer is used, water marks occur on the semiconductor wafer after drying.
In order to avoid this problem, a marangoni dryer for drying a wafer without exposing it to the air, after a chemical solution treatment process and de-ionized water cleaning process, has been suggested. While the marangoni dryer lifts the semiconductor wafer from a bath filled with de-ionized water, or slowly drains the de-ionized water from the bath, it removes the de-ionized water using a difference in surface tension between the IPA and the de-ionized water, by spraying IPA onto the surface of the semiconductor wafer. The marangoni dryer can remove the de-ionized water by using an amount of IPA as small as {fraction (1/10)} of the amount of IPA used by the IPA vapor dryer. However, since the marangoni dryer is easily affected by laminar flow or exhaustion in a semiconductor wafer cleaning apparatus, drying is not uniformly performed over the surface of the semiconductor wafer, thereby forming water marks. In particular, water marks non-uniformly occur when a semiconductor wafer having a large diameter of 12 inches is used.
The present invention is therefore directed to a semiconductor wafer cleaning apparatus and method which substantially overcome one or more of the problems due to the limitations and disadvantages of the related art.
To solve the above problems, it is a first object of the present invention to provide a semiconductor wafer cleaning apparatus which is not affected by an atmosphere and is capable of preventing water marks when a marangoni dryer is used.
It is a second object of the present invention to provide a method for cleaning a semiconductor wafer in which water marks are prevented by properly using a semiconductor wafer cleaning apparatus according to the present invention.
Accordingly, to achieve the first and other objects, there is provided a semiconductor wafer cleaning apparatus. The semiconductor wafer cleaning apparatus includes only one inner bath for performing both chemical solution cleaning and de-ionized water cleaning therein. Also, the semiconductor wafer cleaning apparatus includes a marangoni dryer for both cleaning and drying semiconductor wafers therein. The semiconductor wafer cleaning apparatus includes a loading unit loaded with a cassette on which a plurality of semiconductor wafers are mounted; a moving mechanism for extracting the semiconductor wafers mounted on the cassette of the loading unit and moving the extracted semiconductor wafers into a loader spaced apart from the loading unit; an inner bath spaced apart from the loader, for cleaning the semiconductor wafers with a chemical solution or de-ionized water; a marangoni dryer including a hood for moving the semiconductor wafers from the loader into the inner bath, capable of moving in the xc2x1X-, xc2x1Y-, and xc2x1Z-directions to be tightly sealed to the inner bath; and a knife for supporting the semiconductor wafers loaded into the inner bath, at a lower portion of the inner bath, and moving the semiconductor wafers up and down at a certain speed.
In detail, the marangoni dryer includes slots and a locking unit for mounting the semiconductor wafers mounted on the loader, a hood for drying the semiconductor wafers, an isopropyl alcohol (IPA) supply plate having a plurality of holes so that IPA is uniformly spread onto mounted semiconductor wafers in the hood, and an IPA supply nozzle installed on the IPA supply plate. Accordingly, the marangoni dryer moved in the xc2x1X-, xc2x1Y-, and xc2x1Z-directions is closely adhered to the inner bath, and the semiconductor wafers after cleaning are dried, thereby preventing the marangoni dryer from being affected by laminar flow or exhaustion in the semiconductor wafer cleaning apparatus and preventing water marks from occurring on the surface of the semiconductor wafers.
Recessed portions are installed at both sidewalls of the inner bath, and outer baths are further installed at both sides of the inner bath, covering the recess portions. An exhaust line for uniformly performing exhaustion is further installed at both rear walls of the outer baths. Further, exhaustion is uniformly performed in a case where an exhaust line is installed at the outer baths installed at both sides of the inner bath during drying of the semiconductor wafers, thereby further reducing the occurrence of water marks on the surface of the semiconductor wafers.
In order to achieve the second and other objects, there is provided a method for cleaning a semiconductor wafer. The method includes the steps of loading a cassette on which a plurality of semiconductor wafers are mounted, into a loading unit; extracting the semiconductor wafers mounted on the cassette of the loading unit and moving the extracted semiconductor wafers into a loader spaced apart from the loading unit. The above-mentioned steps are followed by the steps of mounting the semiconductor wafers moved into the loader, into a marangoni dryer; moving the marangoni dryer on which the semiconductor wafers are mounted, into an inner bath spaced apart from the loader; moving the semiconductor wafers from the marangoni dryer into an inner bath and cleaning the semiconductor wafers with a chemical solution and/or de-ionized water.
Subsequently included in the method are the steps of lowering the marangoni dryer to be closely adhered to the inner bath; and lifting the semiconductor wafers at a certain speed from the inner bath containing the de-ionized water, or slowly draining the de-ionized water while nitrogen and IPA fumes are sprayed from the top of the marangoni dryer, so that the chemical solution and/or de-ionized water is removed from the semiconductor wafers using a difference in surface tension between the IPA and the de-ionized water.
If the semiconductor wafers cleaned with the de-ionized water are dried in a state where the marangoni dryer is closely adhered to the bath, the marangoni dryer may be not affected by laminar flow or exhaustion in the semiconductor wafer cleaning apparatus, thereby reducing the occurrence of water marks on the surface of the semiconductor wafers. Finally, exhaustion is uniformly performed by an exhaust line installed at the outer baths installed at both sides of the inner bath during removal of the de-ionized water, thereby further reducing the occurrence of water marks on the surface of the semiconductor wafers.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.